Can someone help me find a "proportioning/seperator valve" for a 1995 Concorde!?!?

Can someone help me find a "proportioning/seperator valve" for a 1995 Concorde!?!?

I have a 1995 Chrysler Concorde (3.3 engine). I am having major problems finding what my mechanic calls a "proportioning/separator valve" for the right rear wheel. Please note, I know practically nothing when it comes to vehicles, and I rely on my mechanic friend to get me through these types of jams. So, after I first bought the car (used of course) my mechanic told me the valve was leaking. I managed to find a similar valve on a 1994 Concorde I found in a junk yard and my mechanic made that valve work, despite telling me it was NOT the proper valve. I did look as hard as possible to find the right valve, but that proved impossible. I was happy my mechanic made this 1994 valve work. It lasted for about 6-8 months with no leaking. However, just recently it has begun to start leaking brake fluid again, very similar to how the original valve did when I bought the car. Now I cannot even find a 1994 Concorde to get a similar valve off of so my mechanic can, yet again, "make it work". I would like to get the RIGHT part, but that is apparently impossible and my mechanic said he could make a 1994 valve work if I can simply find one, again, but this time I have not been lucky enough to do so. Does anyone know how I can get this part? Does anyone happen to have a 1995 Concorde who is willing to sell the proper part? I have included a picture of the current 1994 pull that is installed on my 1995 Chrysler Concorde.